Magnetic fields and the temperature structure of the chromosphere-corona interface

Kopp, R. A.; Kuperus, M.

doi:10.1007/bf00148082

Cited by 89 publications

(26 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Generally the highest filtered continuum intensity (thin black contours) are associated with high magnetic field concentrations. This can be expected since the relation between bright network patches and magnetic field concentration has been known since Kopp & Kuperus (1968). However these network patches do not necessarily coincide with the brightest regions in line intensity and not even necessarily with the brightest regions in the continuum image (upper left panel in Fig.…”

Section: Coronal Outflowsmentioning

confidence: 87%

“…In this context the role of the magnetic field for intensity enhancements and in velocity variations is still not clear. Kopp & Kuperus (1968) first proposed an enhanced magnetic field as a reason for the measured intensity enhancement of UV emission lines in the temperature regime below 10 5 K. Later Reeves et al (1974) observed that in lines formed above 10 5 K the network structure disappears. Based on this, Gabriel (1976) developed a model relating the observed bright EUV network to magnetic flux concentrated at supergranular boundaries of the convective flows at the chromospheric level.…”

Section: Introductionmentioning

confidence: 98%

See 1 more Smart Citation

The correlation between coronal Doppler shifts and the supergranular network

Aiouaz

Peter²,

Lemaire

2005

A&A

View full text Add to dashboard Cite

Abstract. We examine properties of line profiles as found with large raster scans of the solar corona acquired by the UV spectrometer SUMER on board SOHO. The observed regions include an equatorial coronal hole, a polar coronal hole, as well as surrounding quiet Sun areas. In order to reveal the network and remove strong local brightenings, a filter is applied to a continuum image. The filtered continuum image, the intensity image and the dopplergram are used to produce "scatter diagrams" (dispersion plots). We find correlations between the chromospheric network, the Ne  (770 Å) intensity and the Ne  (770 Å) Doppler shift in quiet Sun areas and in coronal holes. We establish that the maximum outflow (blue-shift) at low corona temperatures does not appear in the centre of the network but rather near network boundaries. Furthermore the maximum blue-shift seems to appear in the dark regions in Ne  line intensity, which is in agreement with Wilhelm (2000). The opposite correlation appears for very low intensities (less than half of the average intensity), revealing in these regions a lack of energy to either accelerate the solar wind or produce any detectable radiation. The absence of magnetic field concentration in these regions in a reconstructed magnetogram from a MDI/SOHO series seems to confirm the lack of energy.

show abstract

Section: Coronal Outflowsmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 98%

The correlation between coronal Doppler shifts and the supergranular network

Aiouaz

Peter²,

Lemaire

2005

A&A

View full text Add to dashboard Cite

show abstract

“…Indeed, there are various other numerous proposed physical processes responsible for the formation of spicules. Among others, the compression of the plasma sheet by the magnetic field (Hollweg 1972), Joule heating in the current sheet (Hirayama 1992), thermal conduction from the corona (Kopp & Kuperus 1968;Moore & Fung 1972) and buffeting of anchored magnetic flux by granulation can lead to spicules (Roberts 1979). These and various other mechanisms are discussed by Sterling (2000).…”

Section: Introductionmentioning

confidence: 99%

Two-fluid Numerical Simulations of Solar Spicules

Kuźma

Murawski

Kayshap

et al. 2017

ApJ

View full text Add to dashboard Cite

We aim to study the formation and evolution of solar spicules by means of numerical simulations of the solar atmosphere. With the use of newly developed JOANNA code, we numerically solve two-fluid (for ions + electrons and neutrals) equations in 2D Cartesian geometry. We follow the evolution of a spicule triggered by the time-dependent signal in ion and neutral components of gas pressure launched in the upper chromosphere. We use the potential magnetic field, which evolves self-consistently, but mainly plays a passive role in the dynamics. Our numerical results reveal that the signal is steepened into a shock that propagates upward into the corona. The chromospheric cold and dense plasma lags behind this shock and rises into the corona with a mean speed of 20-25 km s −1 . The formed spicule exhibits the upflow/downfall of plasma during its total lifetime of around 3-4 minutes, and it follows the typical characteristics of a classical spicule, which is modeled by magnetohydrodynamics. The simulated spicule consists of a dense and cold core that is dominated by neutrals. The general dynamics of ion and neutral spicules are very similar to each other. Minor differences in those dynamics result in different widths of both spicules with increasing rarefaction of the ion spicule in time.

show abstract

“…The temperature gradient near the Sun is determined by processes occurring in the lower corona where heat conduction into the chromosphere is very important (Kuperus and .Athays (12) 1967; Kopp and Kuperus, 1968;Kuperus, 1969). In order to proceed without becoming involved in the complexities of the chromospherecorona interface, we will assume that the coronal temperature distribution is spherically symmetric near the Sun, and that the temperature gradient is given by Equation (6) far all heliolatitudes (cf.…”

Section: Governing Equationsmentioning

confidence: 99%